Nanoscale Mass-Spectrometry Imaging of Grain Boundaries in Perovskite Semiconductors
O.J. Usiobo, H. Kanda, P. Gratia, I. Zimmermann, T. Wirtz, M.K. Nazeeruddin, and J.N. Audinot
Journal of Physical Chemistry C, vol. 124, no. 42, pp. 23230-23236, 2020
Incorporation of alkali metals such as Cs+, Rb+, and K+ into hybrid organic-inorganic halide lead perovskites (HOIPs) generally improves the optoelectronic properties of HOIPs. However, it is still uncertain how alkali metals interact and distribute within the HOIPs. There is also a struggle in finding a technique for nanometer-scale structural and chemical characterization without laborious sample preparation or risking severe beam damage of the material during characterization. Here, we have investigated the nanometer-scale distribution of alkali pairs (K-Cs, Rb-Cs, and K-Rb) incorporated into a HOIP using helium-ion microscopy coupled with secondary-ion mass spectrometry (HIM-SIMS) that allows for nanometer-scale elemental and morphological imaging at an unprecedented spatial resolution. HIM-SIMS analysis reveals that Rb segregates at perovskite grain boundaries irrespective of whether it is paired with Cs or K.